[Eeglablist] FFT in EEG signal

[Tim Mullen]

Hi Mohd,

Additionally, for better spectral properties (e.g., reduced variance), you
might consider using a method other than just the fft. For example, Welch's
modifed periodogram (doc pwelch, if you have the signal processing toolbox),
also implemented in EEGLAB's spectopo() routine (which can return average
spectrum across trials as well).

spectopo usage:

*data :  * [num_samples x num_channels x num_trials] data matrix
*frames :   *the number of samples per epoch (size(data,1))
*srate : *the sampling rate
*nfft :   *the fft length (frequency resolution will be sampling_rate /
nfft)
*freqrange* :  a 2-element vector of the frequency range to plot (assuming
'plot','on')
*doplot : *(= 'on' | 'off') whether to plot the spectum for all chans in dB

[Pxx F]  = spectopo(data, frames, srate,'nfft',nfft,'freqrange',
freqrange,'plot',doplot);

type 'doc spectopo' for more parameters and options.

ciao,
Tim

2008/8/30 Mohd Naz <starz_naz at yahoo.com>

> if i want to know frequency content in eeg signal recorded for 30 minutes,
> could i make use FFT?
>
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